Method for preparing edible oil

Abstract

Oil is extracted from vegetable material, such as cottonseed, rapeseed, safflower seed, sunflower seed, and linseed, by mechanically expelling crude oil from the vegetable material and then chemically extracting crude oil from the pulp cakes produced in the expelling step by using a suitable solvent. After the expelling step the oil is separated from the cakes and, thereafter, the mechanically expelled crude oil is passed through a layer of the cakes prior to at least a portion of chemical extraction to filter fine sediment from the expelled oil and thus eliminate separate fine sediment filtering steps of the mechanically expelled crude oil.

What is claimed is: 
     
       1. A process of extracting oil from vegetable seeds comprising the steps of mechanically expelling crude oil from the vegetable seeds to produce vegetable seed cakes and mechanically expelled crude oil,   separating the mechanically expelled crude oil from the cakes,   passing the separated mechanically expelled crude oil through a layer of the separated cakes produced in the expelling step to filter sediment from the mechanically expelled crude oil, and   chemically extracting crude oil from the cakes after said passing step is performed by flowing a solvent through the layer of cakes.   
     
     
       2. A process as claimed in claim 1 in which said layer of cakes is moved on a conveyor during said passing and chemical extraction steps with the passing step being performed at a point along the conveyor upstream of where the chemical extracting step is performed. 
     
     
       3. A process as claimed in claim 2 wherein the chemical extraction step includes a plurality of repetitive flowing steps wherein the solvent is flowed through respective successive sections of the layer of cakes beginning adjacent the downstream end of the conveyor, and the passing step occurs simultaneously with one of the flowing solvent steps adjacent the upstream end of the conveyor. 
     
     
       4. A process as claimed in claim 3 including the step of collecting the mechanically expelled crude oil oil in a service tank prior to combining the separated mechanically expelled crude oil with the cakes to prevent a backflow of solvent into the crude oil. 
     
     
       5. A process as claimed in claim 4 including the step of filtering large size sediment from the separated mechanically expelled crude oil prior to the collecting step for the mechanically expelled crude oil. 
     
     
       6. A process as claimed in claim 1 wherein the seed is selected from the group consisting of cotton seed, rapeseed, safflower seed, sunflower seed and linseed.